KR20170049082A

KR20170049082A - Mg casting alloy having High thermal conductivity and method of manufacturing the same

Info

Publication number: KR20170049082A
Application number: KR1020150150012A
Authority: KR
Inventors: 임현규; 김세광; 양원석; 오건영; 곽태양; 정영길
Original assignee: 한국생산기술연구원
Priority date: 2015-10-28
Filing date: 2015-10-28
Publication date: 2017-05-10

Abstract

According to one embodiment of the present invention, provided is a high thermal conductivity magnesium cast alloy. The high thermal conductivity magnesium cast alloy comprises: 2.0-5.0 wt% of zinc (Zn); 0.5-2.0 wt% of calcium (Ca); and the remaining consisting of magnesium (Mg) and inevitable impurities, wherein the thermal conductivity is 110-150 W/mK or less. As such, the present invention is able to acquire thermal conductivity of 110 W/mK or more.

Description

Technical Field The present invention relates to a high thermal conductivity magnesium alloy and a method for manufacturing the same.

The present invention relates to a high-thermal-conductivity magnesium alloy and a method of manufacturing the same, and more particularly, to a high-thermal-conductivity magnesium alloy used in various components such as electric, electronic, and communication machines.

Recently, as the use of smart phones is rapidly increasing, components for better performance are being used, which causes problems due to heat generation. In addition, LED lighting with low power consumption and long life span is receiving the spotlight to reduce the environmental load, but since the progress of degradation due to resin deterioration is fast, a heat sink which is not needed in the conventional lighting apparatus (bulb or fluorescent lamp) .

An aluminum alloy having excellent thermal conductivity is used as the heat sink material, but aluminum alloy is not suitable for use as a frame of a smartphone because it is difficult to cast a thin plate (thickness of 0.5 mm or less). In Japan, where there are many earthquakes, Japan is promoting lightweight heat sinks for safety in case of emergency. Therefore, there is a growing need to develop alloys that are lightweight but capable of casting thin plates and have excellent thermal conductivity.

Japanese Patent No. 4678373B9 (Feb.

The present invention is directed to solving various problems including the above-described problems, and a high-thermal-conductivity magnesium alloy capable of obtaining a thermal conductivity of 110 W / m · K or more at room temperature, and a method of manufacturing the same. However, these problems are exemplary and do not limit the scope of the present invention.

According to one aspect of the present invention, a high thermal conductivity magnesium alloy is provided. The high thermal conductivity magnesium alloy may contain 2.0 to 5.0% by weight of zinc (Zn), 0.5 to 2.0% by weight of calcium (Ca), and the remainder may be magnesium (Mg) and inevitable impurities.

In the high thermal conductivity magnesium alloy, the thermal conductivity of the magnesium alloy may be 110 W / m · K or more and 150 W / m · K or less.

The high thermal conductivity magnesium alloy may be one or two selected from the group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc) Or more of the above elements in an amount of 0.001 to 1.0% by weight.

In the high-temperature-conduction magnesium-based alloy, the magnesium-based alloy may further contain aluminum (Al) in an amount of 0.001 to 2.0% by weight.

According to another aspect of the present invention, a method of manufacturing a high thermal conductivity magnesium alloy is provided. The method of manufacturing the high thermal conductivity magnesium cast alloy includes the steps of: providing a molten metal containing magnesium; And supplying a source of zinc and calcium (Ca) to the magnesium-containing melt. Wherein the high thermal conductivity magnesium alloy includes 2.0 to 5.0 wt% zinc (Zn), 0.5 to 2.0 wt% calcium (Ca), the balance magnesium (Mg) and inevitable impurities, It may be in the range of 110 W / m · K to 150 W / m · K or less.

The step of supplying the calcium (Ca) source may be a step of charging calcium oxide (CaO).

The step of supplying the calcium (Ca) source may be a step of inputting calcium metal (Ca).

The step of supplying the calcium (Ca) source may be a step of charging the Mg-CaO parent alloy.

The step of supplying the calcium (Ca) source may be a step of charging the Mg-Ca parent alloy.

According to one embodiment of the present invention, as described above, a high thermal conductivity magnesium alloy can be used as a material for manufacturing parts such as electric, electronic and communication parts requiring light, thin and excellent thermal conductivity, and a method for manufacturing the same . Of course, the scope of the present invention is not limited by these effects.

1 to 4 are process flow diagrams schematically illustrating a method of manufacturing a high thermal conductivity magnesium alloy according to an embodiment of the present invention.
FIG. 5 shows the results of measurement of thermal conductivity of magnesium alloy samples at room temperature according to Examples and Comparative Examples of the present invention.
Fig. 6 is a result of a comparative analysis of the microstructure of the magnesium alloy sample of Example 4 and Comparative Example 1 shown in Fig. 5 by a scanning electron microscope.
FIG. 7 shows the results of thermal conductivity comparison of the magnesium alloy samples of Example 4 and Comparative Example 3 shown in FIG. 5 measured in various temperature ranges.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, Is provided to fully inform the user. Also, for convenience of explanation, the components may be exaggerated or reduced in size.

1 to 4 are process flow diagrams schematically illustrating a method of manufacturing a high thermal conductivity magnesium alloy according to an embodiment of the present invention.

Referring to FIG. 1, a method (S100) for producing a high thermal conductivity magnesium alloy according to an embodiment of the present invention includes the steps of providing a magnesium-containing melt (S110), adding zinc (S120), and a step (S130) of adding calcium oxide (CaO) to the magnesium-containing molten metal.

For example, a high thermal conductivity magnesium alloy can be produced by sequentially or simultaneously introducing zinc (Zn) and calcium oxide (CaO) into a magnesium-containing melt. The high thermal conductivity magnesium alloy casted by the method (S100) for producing the high thermal conductivity magnesium alloy includes 2.0 to 5.0% by weight of zinc (Zn), 0.5 to 2.0% by weight of calcium (Ca) Magnesium (Mg) and unavoidable impurities. Here, the calcium may be reduced from the calcium oxide (CaO) added to the magnesium molten metal to form a matrix of a magnesium alloy. At this time, the thermal conductivity of the high thermal conductivity magnesium cast alloy may be 110 W / m · K or more at room temperature.

The calcium oxide added to the magnesium molten metal is applied to the surface of the molten metal in the form of powder and can be reduced to calcium by causing the surface reaction of the molten metal through agitation (surface agitation) of the upper portion of the molten metal. Here, in the surface reaction, the calcium reduced from the calcium oxide is supplied to the alloying element in the magnesium molten metal through the stirring of the calcium oxide applied to the surface of the molten metal, and the oxygen component is released into the atmosphere. This surface reaction can be carried out in the atmosphere, not in an ambient gas.

Wherein the high thermal conductivity magnesium alloy is one or more elements selected from the group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc) May be further added in an amount of 0.001 to 1.0% by weight.

The high thermal conductivity magnesium alloy may further contain 0.001 to 2.0% by weight of aluminum (Al).

For example, when 1.0 to 2.0 wt% of aluminum (Al) is added, the strength and hardness are increased, the flowability of the alloy during casting is improved, the coagulation range is increased and the casting composition is improved, It is easy to handle, and the thermal conductivity is greatly reduced.

In addition, very small amounts of beryllium (Be), for example about 0.001 wt% beryllium, can effectively reduce the oxidation of molten magnesium during casting or welding. Tin (Sn) has an effect of suppressing the occurrence of cracks during hot working and therefore has an effect of increasing the elongation.

Zirconium (Zr) can improve the elongation by reducing the grain size of the magnesium alloy. Zirconium has a lattice constant similar to that of magnesium, so that the zirconium particles formed upon dissolution provide a nucleation site of magnesium in the solidification process, and the addition of zirconium, zinc, rare earth metals, etc. may also have the effect of refining the crystal grains.

Since manganese (Mn) bonds with iron or other heavy metal elements to form an intermetallic compound which is relatively harmless to corrosion resistance, it has an effect of improving corrosion resistance. In addition, in order to improve the fluidity and strength of the molten metal during casting, various elements having a predetermined content may be further added to the magnesium melt.

On the other hand, zinc (Zn) contained in the high thermal conductivity magnesium cast alloy is a typical element added to the magnesium alloy after aluminum (Al), which improves the strength and fluidity of the alloy. However, the addition of a large amount of zinc reduces the thermal conductivity of the magnesium alloy. Zinc is added to the high thermal conductivity magnesium alloy according to an embodiment of the present invention. When the content of zinc is less than 2.0 wt%, the fluidity of the alloy is lowered and it is difficult to use the alloy as a casting alloy. On the other hand, if the content of zinc is 5.0 wt% or more, the thermal conductivity may be degraded. Therefore, the content of zinc in the high thermal conductivity magnesium cast alloy may be limited to 2.0 to 5.0 wt%.

In addition, calcium (Ca) contained in the high thermal conductivity magnesium alloy can improve the oxidation and ignition resistance of the magnesium alloy. Mg ₂ Ca and Ca ₂ Mg ₆ Zn ₃ phases are formed to reduce the content of the elements contained in the magnesium base, thereby facilitating the movement of the electrons, thereby contributing to the improvement of the thermal conductivity. 0.5 to 2.0% by weight of calcium is added to the high thermal conductivity magnesium alloy according to an embodiment of the present invention. If the content of calcium is less than 0.5% by weight, it can not contribute to the improvement of thermal conductivity. On the other hand, when the calcium content is 2.0% by weight or more, the fraction of the Mg ₂ Ca phase having a high brittleness is increased, thereby deteriorating the mechanical properties.

Referring to FIG. 2, a method (S200) for manufacturing a high-thermal-conductivity magnesium alloy according to another embodiment of the present invention includes the steps of providing a magnesium-containing melt (S210), introducing zinc into a magnesium- A step S220 and a step S230 of inputting calcium metal Ca into the magnesium-containing molten metal.

For example, a high thermal conductivity magnesium alloy can be produced by sequentially or simultaneously introducing zinc (Zn) and metal calcium (Ca) into a magnesium-containing melt. More specifically, the high thermal conductivity magnesium alloy casting method implemented by the method (S200) for manufacturing the high thermal conductivity magnesium alloy includes the following: 2.0 to 5.0 wt% of zinc (Zn), 0.5 to 2.0 wt% of calcium (Ca) And the balance of magnesium (Mg) and unavoidable impurities.

The content of zinc and calcium in the high-thermal-conductivity magnesium alloy according to another embodiment of the present invention is the same as that described above with reference to FIG. 1, and thus a detailed description thereof will be omitted.

Referring to FIG. 3, a method (S300) for manufacturing a high thermal conductivity magnesium alloy according to yet another embodiment of the present invention includes the steps of providing a magnesium-containing melt (S310), adding zinc into a magnesium- (S320) and injecting the Mg-CaO parent alloy into the magnesium-containing molten metal (S330).

The Mg-CaO parent alloy means a parent alloy prepared by adding calcium oxide (CaO) to a magnesium-containing molten alloy.

For example, a high thermal conductivity magnesium alloy can be prepared by sequentially or simultaneously introducing zinc (Zn) and a Mg-CaO parent alloy into a magnesium-containing melt. The high thermal conductivity magnesium alloy cast according to the method for manufacturing the high thermal conductivity magnesium alloy (S300) comprises 2.0 to 5.0% by weight of zinc (Zn), 0.5 to 2.0% by weight of calcium (Ca) Magnesium (Mg) and unavoidable impurities. Here, the calcium may be reduced from calcium oxide (CaO) in the production of the Mg-CaO parent alloy, or may be reduced from calcium oxide (CaO) after the Mg-CaO parent alloy is added to the magnesium- .

Referring to FIG. 4, a method (S400) for manufacturing a high thermal conductivity magnesium alloy according to another embodiment of the present invention includes the steps of providing a magnesium-containing melt (S410), adding zinc into a magnesium- (S420), and a step (S430) of adding a Mg-Ca parent alloy to the magnesium-containing molten metal.

For example, a high thermal conductivity magnesium alloy can be produced by sequentially or simultaneously introducing zinc (Zn) and a Mg-Ca parent alloy into a magnesium-containing melt.

The Mg-Ca parent alloy means a parent alloy prepared by adding metal calcium (Ca) to a magnesium-containing molten alloy.

The high thermal conductivity magnesium alloy cast according to the method for manufacturing the high thermal conductivity magnesium alloy (S400) comprises 2.0 to 5.0% by weight of zinc (Zn), 0.5 to 2.0% by weight of calcium (Ca) Magnesium (Mg) and unavoidable impurities.

Hereinafter, an experimental example to which the technical idea described above is applied will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are for the purpose of promoting understanding of the present invention and are not intended to limit the scope of the present invention.

Magnesium alloy samples having different contents of aluminum (Al), zinc (Zn), calcium (Ca) and manganese (Mn) as main components were prepared as samples according to the experimental examples of the present invention, After dissolving in a protective gas atmosphere of SF ₆ + CO ₂ using an electric resistance furnace, magnesium alloy samples of Examples 1 to 12 were produced by using a casting mold. The cast samples were then machined to a diameter of 12.7 mm and a thickness of 2 mm and the thermal conductivity was measured using a NETZSCH LFA 447 instrument.

Meanwhile, for comparison, a magnesium alloy sample of Comparative Example 1 in which zinc (Zn) was added much more than the magnesium alloy samples of Examples 1 to 12 was prepared. The magnesium alloy samples of Examples 1 to 12 A magnesium alloy sample of Comparative Example 2 in which calcium (Ca) was added much more than the sample was prepared.

In addition, the thermal conductivity was measured in the same manner as in the above Experimental Example using magnesium alloy samples of Comparative Example 3 (AZ91D) and Comparative Example 4 (AM60B), which are commercially available magnesium alloys.

Alloy component (% by weight) Remarks Al Zn Ca Mn Mg Example 1 - 2.0 0.5 - Honey. Example 2 - 2.0 1.0 - Honey. Example 3 - 4.0 1.0 - Honey. Example 4 - 4.0 2.0 - Honey. Example 5 1.0 2.0 0.5 - Honey. Example 6 1.0 4.0 0.5 - Honey. Example 7 1.0 2.0 1.0 - Honey. Example 8 1.0 4.0 1.0 - Honey. Example 9 2.0 2.0 0.5 - Honey. Example 10 2.0 4.0 0.5 - Honey. Example 11 2.0 2.0 1.0 - Honey. Example 12 2.0 4.0 1.0 - Honey. Comparative Example 1 - 6.0 - - Honey. Comparative Example 2 - - 3.0 - Honey. Comparative Example 3 9.0 1.0 - - Honey. Commercial AZ91D Comparative Example 4 6.0 - - 0.5 Honey. Commercial AM60B

5 shows the results of measurement of thermal conductivity at room temperature of magnesium alloy samples according to Examples and Comparative Examples of the present invention and Table 2 shows the castability and thermal conductivity of magnesium alloy samples according to Examples and Comparative Examples of the present invention This is the result of comparative analysis.

Casting Thermal conductivity Remarks Good Poor Good Poor Example 1 ○ ○ Example 2 ○ ○ Example 3 ○ ○ Example 4 ○ ○ Example 5 ○ ○ Example 6 ○ ○ Example 7 ○ ○ Example 8 ○ ○ Example 9 ○ ○ Example 10 ○ ○ Example 11 ○ ○ Example 12 ○ ○ Comparative Example 1 ○ ○ Comparative Example 2 ○ ○ Comparative Example 3 ○ ○ Commercial AZ91D Comparative Example 4 ○ ○ Commercial AM60B

5 and Table 2, the room temperature thermal conductivity of the magnesium alloy samples of Examples 1 to 12 was 110 W / m · K or more and 150 W / m · K or less, respectively. It can be confirmed that the samples according to the embodiments of the present invention have the same or higher thermal conductivity than the magnesium alloy samples of Comparative Example 1 and Comparative Example 2. [ It can also be seen that the samples according to the embodiment of the present invention have markedly higher thermal conductivity values than the magnesium alloy samples of Comparative Examples 3 and 4.

However, in the case of the magnesium alloy samples of Comparative Examples 1 and 2 of the present invention, when zinc (Zn) and calcium (Ca) elements are used alone, they have excellent thermal conductivity characteristics, .

Fig. 6 is a result of a comparative analysis of the microstructure of the magnesium alloy sample of Example 4 and Comparative Example 1 shown in Fig. 5 by a scanning electron microscope.

Specifically, as a result of analyzing the microstructure of a magnesium alloy sample by a scanning electron microscope, a back scattering electron beam of a scanning electron microscope was used to clearly distinguish each phase constituting the sample Microstructures were observed. 6 (a) is a microstructure of a magnesium alloy sample of Example 4 of the present invention, and Fig. 6 (b) is a microstructure of a magnesium alloy sample of Comparative Example 1. Fig.

Referring to FIG. 6, it can be seen that the magnesium base of the magnesium alloy sample of Comparative Example 1 has a difference in contrast. Generally, when the magnesium alloy is solidified, the amount of the alloy element in the alloy base decreases, and the alloy element is released. At this time, since the solidification rate is faster than the release rate at a certain temperature or lower, alloying elements are not released on the superfine resin of the alloy. Therefore, the content of alloying elements varies in the same crystal grains.

As a result, this difference in lightness means that the amount of the alloying element in the matrix is unevenly distributed. On the other hand, in the case of the microstructure of the magnesium alloy sample of Example 4, it is not possible to distinguish the difference in light and shade within the matrix, and it can be seen that the alloy elements in the matrix exist uniformly.

Also, in the case of heat transfer from a metal, it can be explained as the movement of free electrons. These free electrons move to the surface or lattice of the metal to transmit heat or electricity. In the case of the magnesium alloy sample of Comparative Example 1, since the non-uniformly existing alloying elements in the magnesium matrix affect the magnesium crystal lattice, the movement of the electrons is disturbed and therefore the thermal conductivity is higher than that of the magnesium alloy sample of Example 4 It can be seen that it is greatly deteriorated.

FIG. 7 shows the results of thermal conductivity comparison of the magnesium alloy samples of Example 4 and Comparative Example 3 shown in FIG. 5 measured in various temperature ranges.

Referring to FIG. 7, the magnesium alloy sample of Example 4 satisfied a thermal conductivity of not less than 110 W / m · K at not only room temperature but also high temperature. On the other hand, it can be confirmed that the magnesium alloy sample of Comparative Example 3 has a significantly lower thermal conductivity value than the magnesium alloy sample of Example 4.

This is because the zinc (Zn) element contained in the magnesium alloy sample of Example 4 improved the fluidity of the magnesium alloy and the calcium (Ca) element contributed to the improvement of the thermal conductivity by facilitating the movement of electrons in the magnesium base Respectively.

As described above, the magnesium alloy according to the embodiments of the present invention contains 2 to 5% by weight of zinc (Zn) and 0.5 to 2.0% by weight of calcium (Ca) It can have thermal conductivity.

In addition, the magnesium alloy according to the embodiments of the present invention can be used as a casting material for manufacturing parts such as electric, electronic and communication parts which are light, thin and require excellent heat conduction.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims

(Mg) and inevitable impurities, and a thermal conductivity of 110 W / m · K or more and 150 W / m · K or more / m · K,
High thermal conductivity magnesium alloy.

The method according to claim 1,
0.001 to 1.0% by weight of at least one element selected from the group consisting of titanium (Ti), beryllium (Be), tin (Sn), zirconium (Zr), strontium (Sr), scandium (Sc) doing,
High thermal conductivity magnesium alloy.

The method according to claim 1,
The magnesium cast alloy may further contain 0.001 to 2.0% by weight of aluminum (Al)
High thermal conductivity magnesium alloy.

Providing a molten metal containing magnesium; And
Introducing a source of zinc and calcium (Ca) into the magnesium-containing melt;
Lt; / RTI >
A method of manufacturing a high thermal conductivity magnesium alloy,
The high thermal conductivity magnesium magnesium alloy,
(Mg) and unavoidable impurities, and a thermal conductivity of 110 W / m · K or more and 150 W / m · K or more, / m · K, wherein the ratio of the total mass of the magnesium-based alloy to the total mass of the magnesium-

5. The method of claim 4,
Wherein the step of introducing the calcium (Ca) source is a step of introducing calcium oxide (CaO).

5. The method of claim 4,
Wherein the step of introducing the calcium (Ca) source is a step of charging metallic calcium (Ca).

5. The method of claim 4,
Wherein the step of introducing the calcium (Ca) source is a step of introducing a Mg-CaO parent alloy into the high-heat-conduction magnesium alloy.

5. The method of claim 4,
The step of introducing the calcium (Ca) source may include the step of introducing a Mg-
METHOD FOR MANUFACTURING HIGH TRANSDUCED MAGNESIUM ALLOY.